On 28 February 2025, the Academy of Experts (UK) held the “Expert Witness - Under the Spotlight” seminar, wherein panels of experts and counsel discussed the role of expert witnesses, their overriding duty to be impartial and independent, and how these responsibilities actually play out in practice.

Our Senior Partner, Vatsala Ratnasabapathy, who heads our Construction, Arbitration and Engineering practice, was invited to be a panellist at the event, where she shared her perspective as counsel on the use of expert witnesses in both litigation and arbitration proceedings. She drew extensively from both her own experience, as well as existing jurisprudence from our domestic courts and from abroad, to share insightful and practical tips for engaging with expert witnesses.

It is an essential cornerstone of expert evidence that the expert witness owes an overriding duty to the court and/or arbitration tribunal. It is critical that the expert remain independent and impartial, as so far as possible, when providing his expert opinion. This requirement is clearly set out within Order 40A, r. 2 of the Malaysian Rules of Court 2012, at Part 35 of the English Civil Procedure Rules (“CPR”), and within the Expert Witness Code of Conduct set out in the Uniform Civil Procedure Rules of the various Australian states.

Considering this requirement, what role does counsel play in the preparation and presentation of expert evidence? Should counsel be involved in the drafting of expert reports at all? How can counsel assist the court in ensuring that expert evidence remains impartial and independent, whilst continuing to advance their client’s case? These critical questions were thoroughly discussed by the panellists, with Vatsala Ratnasabapathy referencing recent decisions from the United Kingdom and Australia to help shed some light on this complicated, but critical, topic.

Landel Pty Ltd v Insurance Australia Limited [2021] QSC 247

In this Australian case, the plaintiff company, which owned and operated a shopping complex, brought proceedings against the defendant insurance company after monsoonal rains and flooding resulted in water entering the shopping complex on several separate occasions. The central issue before the Supreme Court of Queensland was whether the physical circumstances of the inundation of water into the shopping complex fell within the definition of “flood” in the insurance policy.

In support of their claims, both parties called on experts to identify the cause of the inundation of the shopping centre. However, the Court was extremely critical of the presentation and substance of the plaintiff expert’s reports, which the Court described as “prolix and disorganised”, while also containing faults which went beyond matters of expression and presentation. The Court criticised the plaintiff lawyers for not involving themselves in the drafting of the expert reports. While noting that lawyers must not, of course, coach expert witnesses, or otherwise influence the substance of an expert report, “it is permissible, and usually desirable, that lawyers do become involved in the editing of expert reports so that they present material in a way which is accessible and comprehensible, and do not contain irrelevant material.”

The Court went even further and provided that conferences between the expert and the plaintiff lawyers should have been held to improve the reports, stating that “[c]onferences like this are a proper, necessary part of preparing a case”. In the Court’s opinion, these conferences would have identified the significant contradictions, errors and gaps in reasoning within the plaintiff expert’s report, noting that “[i]t is permissible for matters of substance like this to be drawn to an expert’s attention in conference with lawyers, and remedied if the expert is able and willing to do so.” Furthermore, such involvement by the plaintiff lawyers would have allowed them to evaluate the strength of the case they were advancing, and make adjustments to their strategy before trial.

This case is extremely illuminating as the Supreme Court of Queensland has stated in clear terms that counsel is allowed, indeed expected, to be involved in the draft and preparation of expert reports, whether by way of conference with the expert or by direct editing of the report itself. Of course, counsel must always be cautious not to coach the expert, or otherwise influence the substance of the report. However, in the interests of justice, it is both necessary and expedient that counsel assist the expert in presenting a coherent and cogent expert report, dealing with the relevant factual and legal issues.

New Aim Pty Ltd v Leung [2023] FCAFC 67

This matter was an appeal heard before a panel of 5 judges of the Federal Court of Australia. In these proceedings, the plaintiff company claimed that the first defendant had unlawfully disclosed confidential information regarding the identity and contact details of its Chinese suppliers to the second and third defendant companies, in breach of his equitable obligations, his employment contract and/or section 183 of the Corporations Act 2001 (Cth).

In support of their claims, the plaintiff company had adduced an expert report by the managing director of a supplier sourcing company (”the expert company”). The report was fairly unusual in that the bulk of the report dealt with factual material, as it set out the expert company’s own processes when identifying and securing reliable suppliers in China. The “opinion” portion of the expert report consisted of only 5 paragraphs.

At first instance, the trial judge had dismissed the plaintiff’s claims against each of the three defendants, in part due to the trial judge’s rejection of the plaintiff’s expert report. The trial judge had significant concerns as to the plaintiff expert’s independence as:

1. The instruction letter from the plaintiff solicitor was issued just one day before the plaintiff expert finalised her report;
2. The plaintiff expert disclosed during cross-examination that she had “a couple of conversations” with the plaintiff solicitors, and had sent drafts of her report for comment; and
3. The draft report was likely drafted by the plaintiff solicitors based on materials provided by the expert company.

On appeal, the court found that the trial judge had erred in rejecting the whole of the plaintiff expert’s opinion. In particular, the appellate judges found that the inference that the plaintiff expert and solicitors had acted improperly due to the short time between the letter of instruction and the final report was unfounded, as it was common practice for parties to only issue letters of instruction near the completion of the report. The Federal Court of Australia further explained that it is quite normal for solicitors and experts to discuss the formulation of the questions to be answered by the experts. This is especially true when engaging experts in a specialised field of scientific knowledge, so as to avoid nonsensical questions or questions which miss the real issues.

The Court went further and noted that, while in typical cases the expert would ordinarily draft their own report, there are situations which may arise whereby the legal practitioners may prepare or draft the report themselves, as they may when preparing affidavits or witness statements for fact witnesses. For example, there may be physical, language or resource difficulties. However, the Court noted:

“Where these situations arise, care must be taken to ensure that the legal practitioner does not suggest what the expert’s evidence should be and that the report is drafted from what the expert has communicated to the legal practitioner as fact or what the expert has assumed or what the expert’s opinion is. Leaving aside formal matters or instructions or assumptions the expert is required to make, it is difficult to conceive of a situation in which a legal practitioner, acting appropriately and ethically, could draft an expert’s report otherwise than on the basis of what the expert had communicated to the legal practitioner to be his or her evidence.”

It is indeed interesting to see that the Australian courts permit lawyers to get directly involved in the drafting of expert reports. It may be that the court here was willing to allow this due to the unique nature of this expert report, which primarily consisted of factual material rather than expert opinion. It remains to be seen if Malaysian courts would be so accepting of such an expert report.

Andrews and others v Kronospan Ltd [2022] 201 ConLR 1

This English case involved a group litigation brought by households in Chirk, Wrexham, against a wood processing and wood product manufacturing plant, wherein the 159 claimant residents claimed that dust, noise and odour omissions from the defendant’s plant had caused them public and/or private nuisance. In support of their claim, the parties obtained leave to rely on expert evidence regarding dust dispersion modelling, as well as dust analysis and monitoring.

The issue with the expert evidence in this case primarily concerned the joint report for the dust analysis evidence. Under English law, specifically 35PD.9 of the Practice Directions supplementing the CPR, neither parties nor their legal representatives are to attend expert discussions, unless ordered by the Court or agreed by all parties. Even when legal representatives do attend, they should not intervene in the discussion unless asked questions by the experts or to advise them on the law.

In breach of these requirements, and without any disclosure to the defendant expert or defendant solicitors, the claimant expert had:

1. Provided the claimant solicitors with various iterations of the working draft of the joint statement;
2. Received and incorporated comments on issues of substance from the claimant solicitors in the draft; and
3. Provided detailed updates to the claimant solicitors on the progress and content of the joint discussions.

Due to these breaches, the defendant applied to revoke the permission of the claimants to rely on the evidence of the claimant expert. The claimant solicitors conceded that the above interactions were in breach of the CPR requirements, but submitted that it would be disproportionate to revoke the permission as a substantial amount had been spent on expert fees over the three years of the expert’s engagement.

The Court reviewed the evidence and acknowledged that while the majority of the 68 comments made by the claimant solicitors on the working draft related to typographical and formatting errors, there were at least 16 comments relating to “advice and suggestions as to content”. The Court’s primary concern was that the communication between the claimant expert and claimant solicitors indicated that the expert’s approach was more of an advocate for the claimants, rather than that of an independent expert. In reaching this conclusion, the Court highlighted how the claimant expert had sent the first draft of the joint statement to the claimant solicitors unsolicited, and regularly sought their input on how to support the claimants’ case.

Ultimately, the Court decided to revoke the claimants’ permission to rely on their present expert as they could not be sure of his impartiality, but allowed the claimants to appoint another expert instead.

As a result of the claimant expert and claimant solicitors’ actions, the 159 households - all of modest means - wound up wasting £255,000 in expert fees alone, and would have to incur further substantial fees to appoint a new expert. This is a sobering reminder to practitioners on the potential consequences of failing to abide by the expected code of conduct. It is not just counsel who feels the sting, but our clients who are jeopardised by ill-taken actions. It behooves every lawyer to be mindful of the legal requirements and ethical boundaries governing their interactions with expert witnesses.

Glover and another v AXA XL Insurance Company Ltd (formerly known as XL Catlin Insurance Company UK Ltd) 214 ConLR 252 / [2024] EWHC 1257 (TCC)

In this case, the King’s Bench Division of the Technology and Construction Courts of England and Wales had cause to examine when legal advisers may intervene in the preparation of a joint statement. Here, the claimant solicitors had made substantial edits to the draft joint report on the basis that the draft did not correctly address the pleaded issues. However, they did not bring this to the attention of the defendant expert or defendant solicitors. Rather, it was represented as amendments made by the claimant expert.

The Court reiterated that, as a rule, legal advisers must not be involved in either negotiating or drafting the experts’ joint statement. Legal advisers should only invite the experts to consider amending their draft joint statements in exceptional circumstances where there are serious concerns that the court may misunderstand or be misled by the terms of that joint statement. Any such concerns should be raised with all experts involved in the joint statement.

The claimant solicitors eventually conceded that their actions had failed to meet the standards required, particularly their failure to notify the defendant expert or the defendant solicitors of their substantial amendments to the draft joint statement. As a result, there had been an impermissible interference in the expert statement process.

Consequently, the Court revoked the claimant’s leave to rely on that expert, and directed that the claimant appoint a new expert leading up to the trial.

American Arbitration Association’s Handbook - A Divergent Approach?

Having considered these cases, it is also instructive to refer to Chapter 31 of the American Arbitration Association’s Handbook on Arbitration Practice, which takes a somewhat divergent approach:

“Counsel has more freedom in preparing an expert to testify in arbitration and fashioning the expert’s written report. In litigation, anything a testifying expert witness considers in forming an opinion - facts, data, and sometimes communications with others - can be fair game for discovery. For this reason, counsel may hesitate to share information or strategy with the testifying expert for fear of having to turn that over. Counsel may also hire a consulting expert as an extra measure of work-product security.

Expert discovery is more limited in arbitration. Parties typically disclose the identity of their experts along with expert reports and related exhibits. Unless ordered by the arbitrator or agreed to by the parties, parties often do not depose experts. Thus, counsel should feel more comfortable providing experts with all information, whether sensitive, relevant or damaging, and exchanging thoughts and ideas with the expert. This approach can lead to a focused and powerful expert report, a well-prepared expert, and reduced costs for consulting experts or other mechanisms designed to protect otherwise discoverable work product.

Given these considerations, counsel should actually participate in drafting expert reports or detailed outlines. While such practice may not be advisable (or even allowed in some jurisdictions) in litigation, it can be a best practice in arbitration. Counsel can help make the final expert report more persuasive and less subject to attack on cross-examination. Counsel may even continue to refine the expert’s opinion after the reports are exchanged. Facts or data may change or new information may surface. Since experts are less frequently deposed in arbitration, changes to final reports (if even allowed) may not be as damaging as they would be in litigation, where experts are typically deposed and any report changes are fully exposed on cross-examination.”

Thus, while the independence and impartiality of an expert witness remains the heart of expert evidence, it is clear that the manner in which this is enforced varies from country to country, from litigation to arbitration. It is incumbent on every lawyer to familiarise themselves with the requirements of the jurisdiction they are operating in. Failure to abide by the rules can lead to the complete dismissal of the expert evidence, resulting in significant wasted costs, the loss of winnable proceedings, and even claims against the lawyers themselves.

Final Thoughts

Overall, the Expert Witness - Under the Spotlight! seminar was a fascinating deep-dive into the role and expectations of expert witnesses, and how lawyers should navigate this critical but complicated aspect of litigation. The audience were engaged and curious, asking incisive questions of the panellists. Vatsala Ratnasabapathy was encouraged to hear the questions posed by experts and practitioners alike, and to be able to share her perspective on the myriad issues that crop up in the use of expert witnesses. The discussion was further enriched by perspectives shared by distinguished practitioners and experts such as Soh Lieh Sieng, T. Kuhendran, Wong Hin Loong, Kee Meng Fai, Adrian See, Nick Powell, Peter Hiebler, and Ashish Chakravarti. The discussions were rewarding and fruitful, highlighting the importance of collaboration between expert witnesses and legal practitioners.

Acknowledgments: Zain & Co. wish to thank the Academy of Experts UK for inviting our partner, Vatsala Ratnasabapathy to share her insights and our pupil-in-chambers, Cindy Lee Sze Wern, for her diligent assistance in preparing this article.